This invention relates in general to prefabricated residential housing components, and more particularly to a prefabricated fireplace having stovelike air circulation.
The demand for an energy efficient prefabricated fireplace has grown significantly during the past several years in response to the concurrent increases in fossil fuel costs and in residential construction labor costs. As home heating fuel prices have risen, the attractiveness of wood as an alternative fuel and of an efficient fireplace as a heat distributor has been widely recognized, especially since wood is a renewable resource of domestic origin. As the cost of skilled labor for masonry has risen, prefabricated efficient fireplaces have become a cost-effective means to meet the demand for wood-burning home heating systems.
By its nature, the process of residential construction includes certain hazards for custom custom-built masonry, so that a custom-built fireplace may be damaged or improperly assembled during its construction, forcing delays and additional material costs or resulting in poor performance. However, even prior prefabricated fireplaces have featured installation deficiencies which expose uncured concrete to construction hazards for several days. For instance, U.S. Pat. No. 3,466,000 discloses a prefabricated fireplace with a reinforcing frame, the longitudinal reinforcing members of which extend below the bottom of the ashbox to be mounted in an uncured concrete base. The prefabricated fireplace must remain in place with the longitudinal reinforcing members extending into the base while the base concrete cures without placing the weight of the fireplace, which is typically 8,000 to 13,000 pounds, on the base. Therefore, substantial support arrangements must be made for the fireplace, which arrangements may obstruct other construction activities during the cure process. The cure process normally takes seven days in warm weather, and a longer period as temperatures drop.
Furthermore, prior prefabricated fireplaces have provided only the traditional open firebox and flue, which features involve inherent disadvantages. A large fraction of the hot air produced by a wood fire in an open firebox escapes through the open chimney without reaching a house's occupants, and the fire draws cold outdoor air for combustion oxygen into the house through unsealed doors and windows. The interior of the house is warmed only by radiation of the fire and the fireplace masonry, and can be subject to irritating smoke and ash whenever outdoor winds blow these materials back down the flue.
United States Pat. No. 2,430,393 discloses air heater apparatus which includes a closed firebox and flue. The apparatus burns gas behind a sealed window, drawing new oxygen from a direct vent to the outside. The hot fire exhaust circulates through a heat exchanger baffle on its way to the flue, and there transfers some of its heat to room air which circulates through a separate duct network. Therefore, the room receives some exhaust heat as well as fire radiation without exposure to flue backwash or cold outdoor air drawn by the fire. However, this circulation system has heretofore been unadaptable to the use of wood fuel because the need to load wood by hand was incompatible with the need for a sealed window between the fire and the room.